Out of Africa, into China
Our intrepid ancient ancestors left Africa hundreds of thousands of years earlier than thought.
Modern humans left Africa to colonise the world over 180,000 years ago. But their ancient ancestors, the hominins, were also accomplished travellers.
Hominin remains first appear in Ethiopia 2.8 million years ago. By 2.12 million years ago, they were in Shangchen in south-eastern China. That’s the finding of a paper published in Nature last July from Zhaoyu Zhu from the Chinese Academy of Sciences and colleagues.
The new finding pushes back the previous record from Dmanisi, Georgia, by about 270,000 years. The date for hominin habitation here goes back a mere 1.85 million years.
Moreover to reach Shangchen from Ethiopia, required a trek of 14,000 km, more than double the trekking distance to Dmanisi.
Previously, a hominin skullcap and teeth belonging to Homo erectus were found in south-eastern China. These were dated to 1.63 and 1.7 million years old respectively. Zhu’s report is not based on skeletal remains but on 96 stone artefacts that were clearly worked by hominins. The tools, mostly made of quartzite and quartz, include scrapers, points, borers and hammers. Fragments of antelope, deer and pig bones found in the same layers, suggest the tools had been put to good use.
However, as anthropologist John Kappelman from the University of Texas at Austin points out, the researchers did not report evidence of cut marks on the bones, or residues of biological material on the tools.
The stone artefacts were unearthed from the steep cliff face of what’s known as the Loess plateau. Loess is a type of sediment that accumulates from windblown dust. To date these sediments, Zhu and colleagues used palaeomagnetic dating. It relies on the fact that the earth’s magnetic field flips at random reversals – what was north becomes south. Like tiny magnets, iron-containing minerals in sediment particles register the polarity of the time.
This analysis dated the 17 sediment layers bearing the tools from 2.12 million to 1.26 million years, indicating hominins had occupied this region for 860,000 years – a period when the climate fluctuated from warm and wet to cold and dry.
The findings attest to the adaptability of these ancient, intrepid hominins.
An artist’s impression of Homo erectus, who possibly arrived in China more than two million years ago.